Fix signedness mp3 stream compiler warning.

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/mp3inputstream.cc

@@ -138,7 +138,7 @@ MP3InputStream::read_frames (std::vector<float>& samples, size_t count)
   const auto end   = begin + min (count * m_n_channels, m_read_buffer.size());
   samples.assign (begin, end);
   m_read_buffer.erase (begin, end);
-  m_frames_left -= samples.size() / m_n_channels;
+  m_frames_left -= count;
   return Error::Code::NONE;
 }
 

src/mp3inputstream.hh

@@ -16,7 +16,7 @@ class MP3InputStream : public AudioInputStream
   int         m_n_values = 0;
   int         m_n_channels = 0;
   int         m_sample_rate = 0;
-  int         m_frames_left = 0;
+  size_t      m_frames_left = 0;
   bool        m_need_close = false;
   bool        m_eof = false;
   State       m_state = State::NEW;